The number of Lyme disease cases in the US has been recently estimated by the CDC at 300,000 cases/year. This is major public health concern. Currently available diagnostics rely on detection of the antibody response (serology) to Borrelia burgdorferi, the causative agent of Lyme disease. However, serological tests are not accurate during the early stages of Lyme disease. Direct detection of B. burgdorferi antigens within patient samples may be the only solution to an accurate early diagnosis. This application focuses on validating the presence B. burgdorferi VlsE protein in patient samples. VlsE was recently determined to accumulate in a nonhuman primate model of Lyme disease. In addition, the project seeks to identify new diagnostic biomarkers for Lyme disease by utilizing a novel biomarker discovery platform termed, In vivo Microbial Antigen Discovery or InMAD. The overall goal is to identify multiple early Lyme disease biomarkers that can be targeted by a rapid and sensitive immunoassay.